OM 51 . THE ASTRONOMICAL JOURNAL VOLUME 97, NUMBER 2 FEBRUARY 1989 97. ICCD SPECKLE OBSERVATIONS OF BINARY STARS. IV. MEASUREMENTS DURING 1986-1988 FROM THE KITT PEAK 4 m TELESCOPE Harold A. McAlister,a) William I. Hartkopf,a) James R. Sowell,10 1989AJ and Edmund G. Dombrowski“’ Center for High Angular Resolution Astronomy, Georgia State University, Atlanta, Georgia 30303 OttoG. Franz3) Lowell Observatory, Flagstaff, Arizona 86001 Received 29 August 1988; revised 12 October 1988 ABSTRACT One thousand five hundred and fifty measurements of 1006 binary star systems observed mostly during 1986 through mid-1988 by means of speckle interferometry with the KPNO 4 m telescope are present- ed. Twenty-one systems are directly resolved for the first time, including new components to the cool supergiant a Her A and the Pleiades shell star Pleione. A continuing survey of The Bright Star Cata- logue yielded eight new binaries from 293 bright stars observed. Corrections to speckle measures from the GSU/CHARA ICCD speckle camera previously published are presented and discussed. I. INTRODUCTION for the 1983-1984 data is due to the somewhat lower quality This paper presents further results from a continuing pro- of the calibration data available for that particular time peri- gram of binary star speckle interferometry carried out at the od. We now adopt a calibration based upon the mean of all 4 m Mayall telescope at Kitt Peak National Observatory. A the scale and orientation measurements that we have deter- detailed description of the observational technique and in- mined since the initiation of our ICCD speckle-camera sys- strumentation, and of the methods of data reduction, analy- tem. sis, and calibration, can be found in Paper II (McAlister et Using a laboratory spectrometer, we have carefully deter- al. 1987b) of this series. We have employed those same mined the effective wavelength of the Strömgren^ filter used methods to derive the results presented here. for the calibration observations. A correction for the tem- peratures of the individual calibration stars was also deter- II. calibration revisions mined by convolving the filter response against blackbody curves appropriate to the stars we observed. Although the In the course of the reduction of the observations obtained shift in the y effective wavelength is small, amounting to an for this paper and in a series of analyses of binary star orbits overall difference in scale of 0.1 %, we did find the scatter to based upon all of our previously published speckle data, we be measurably reduced among the collected scale values have found it necessary to revise the calibration basis for the once this temperature effect was included. We point out that measurements published in the three earlier papers of this there is no corresponding temperature effect for the program series ( McAlister 1987a,b; huetal. 1987). The calibra- stars; thus it is not necessary to apply a temperature correc- tion of our speckle observations continues to be based upon tion for stars other than calibration stars. the insertion of a double-slit mask at a pupil to produce a Residuals to newly determined double star orbits for some fringe pattern within speckle images and is carried out exact- two dozen binaries showed a consistent discontinuity at the ly in the manner described in McAlister ( 1977), the initial transition between the old photographic speckle data and paper from the speckle program begun by the first author in the new ICCD data. A thorough investigation of this effect 1975. The mask is aligned E-W and the speckle camera is showed that the cause of this step distribution of the residu- mounted at the Cassegrain focus so that north is in the Y als is due to the effective pixel geometry as determined by the direction; thus the fringe pattern produced by the double-slit autocorrelator. Although the CCD has pixels that are mask provides a spatial calibration in the X coordinate. This square, the final pixel shape is determined not by the chip but method of determining the scale and orientation calibration by the redigitization done by the autocorrelator. The CCD has served very well as a truly external means of converting camera electronics reads out the chip and converts the digi- the linear measures from speckle power spectra or autocor- tal information into an analog video signal, specifically into relograms into angular measures on the sky. The revision we standard RS-170 video. The autocorrelator then digitizes describe here has three distinct causes. the video into approximately the same format as exists on the The greatly expanded collection of calibration data now CCD, but, we discovered, with a slight timing mismatch so available to us shows that the scale value at the speckle focal that one unit in Y is not exactly equal to one unit in X. The plane of the ICCD camera has been remarkably constant precise mismatch was measured simply by rotating the cam- since the digital camera was first used in 1982 at the 4 m era 90° and taking calibration and binary star data in the telescope. This has enabled us to determine a mean scale that orthogonal direction. Analysis of these data gave a correc- has the primary effect of increasing the angular separations tion factor for the nonsquare pixelation such that for our data obtained during 1983-1984 by 1.5%, changes to other epochs being insignificantly small. The larger change Y/X= 1.0351 +0.0030. a) Visiting Astronomer, National Optical Astronomy Observatories. This effect is therefore position-angle dependent. NOAO is operated by the Association of Universities for Research in As- In Fig. 1 we show residuals for two binary star systems tronomy, Inc., under contract with the National Science Foundation. before and after the combined calibration effects discussed 510 Astron. J. 97 (2), February 1989 0004-6256/89/020510-22$00.90 © 1989 Am. Astron. Soc. 510 © American Astronomical Society • Provided by the NASA Astrophysics Data System OM 51 . 511 McAlister étal. : binary stars 511 97. 0.450 proximate scales of 0.0052 or 0.0088 arcsec per pixel were 0.440 normally used, except during the rare periods of very poor seeing (average stellar profile FWHM in excess of 3 arcsec) 0.430 when a lowest magnification of 0.016 arcsec per pixel is used 1989AJ « + 0.420 * . and then only for more widely separated and brighter bina- ries. Vector autocorrelograms were produced in real time at McA 55 (19307 + 2748) . 0.410 the telescope and subsequently reduced and analyzed in the CHARA image-processing laboratory at GSU in Atlanta. ? 0.400 Table I contains observational and catalog information 'S 0.390 for the 21 newly resolved stars presented in this paper. As was initiated in Paper II, we assign each newly resolved star 1 0.380 a CHARA number that continues from the last number as- I ^ 0.370 signed in Paper III. Two hundred fifteen systems have been Js newly resolved to date in this continuing program. The last I 0.360 - ADS 11111 (18095 + 0401) column in Table I shows whether the system is a spectro- scopic (SB), composite spectrum (Spm), or occultation 0.350 (Occ) binary, a third component discovered in the course of 0.340 observing a previously known visual binary (Tri), a newly discovered binary resulting from a survey of The Bright Star 0.330 Catalogue (Hoffleit 1982), or a Ban star discovered as a 0.320 -I I L I i i L. result of our attempts to find binaries among this class of 1976 1978 1980 1982 1984 1986 1988 stars. Two stars in the Pleiades cluster have been newly re- Epoch of Observation solved, the first (HD 23568) being indicated as double from occultation observations and the second being the famous Fig. 1. The effect of the correction for nonsquare pixelization result- ing from the digitization by the vector autocorrelator is shown for two shell star Pleione, which The Bright Star Catalogue notes as binary star systems. In both cases, the plus signs are for angular-sepa- being a suspected long-period spectroscopic binary. We have ration measures determined from speckle data obtained prior to 1982 observed Pleione on several occasions during the last few using a photographic speckle-camera system, light squares are mea- years without having detected this companion. These nega- sures from the ICCD camera and autocorrelator before scale correc- tive results do not contradict the present observation in tion, and dark squares are the corrected measures. The scale correc- which the weak autocorrelation peak indicates a large mag- tion clearly eliminates the discontinuity apparent in uncorrected data. nitude difference, a situation in which seeing and instrumen- During the observation interval, McA 55 decreased in position angle tal parameters make detection problematic. from 190° to 160°, while ADS 11111 changed from 340° to 315°. We also report a new companion to the M5 Ib-II star a Her A, the brightest member of the system ADS 10418. The B component of the previously known system is itself a com- above are applied to the data. The agreement between the posite-spectrum star. Reasonable assumptions regarding the older photographic material and the more recent ICCD data mass of the cool supergiant and the distance to the star lead is greatly improved by correcting the data for the effects to a rough estimate of 100-150 yr for the period of the newly described above. The average change in angular separation is discovered companion. We have learned from Dr. Myron A. approximately an increase by 2.5%, while the average Smith (private communication) that his radial-velocity change in position angle is about 0°5.